1. Field of the Invention
A stake/post driver for use with a handheld jack hammer to mechanically drive a stake or post into the ground or other support surface.
2. Description of Prior Art
Driving posts into the ground can be a labor intensive job. It would of course be a benefit to have a mechanical device that could be placed over the upwardly directed end of a post to be driven into the ground that would provide a hammering force to the upwardly directed end of sufficient force and frequency to drive the downwardly directed post end into the ground to the desired depth. Because posts must often be driven into the ground at remote locations, such as when erecting fences and the like, it would be a further benefit to have a post driving device that was lightweight.
U.S. Pat. No. 5,806,608 shows an air-driven post driver that includes a hammer assembly and post receiving assembly. The hammer assembly includes an air-driven piston hammer slidably disposed within a cylinder bore of a cylinder body having a circumference compressed air groove of a first groove width formed into a cylinder wall that defines the cylinder bore and an upper discharge port and a lower discharge port. The piston hammer includes an upward thrusting air passageway and a downward thrusting air passageway. The upward thrusting air passageway includes a radially oriented upward intake passageway and a longitudinally oriented upward discharge passageway. The upward discharge passageway is a length greater than one half the length of the piston hammer. The downward thrusting passageway includes a radially oriented downward intake passageway and a longitudinally oriented downward discharge passageway having a threaded downward discharge port. The downward discharge passageway is of a length greater than one-half the length of the piston hammer.
U.S. Pat. No. 5,494,117 teaches a metal fence post driving apparatus formed by a platform rearwardly supported by the three point hitch of a conventional tractor and having a fluid pressure generating unit on the platform driven by the tractor power takeoff. A mast having a top end portion rotatable about its vertical axis pivotally supports a boom intermediate its ends for horizontal and vertical pivoting movement of its respective end portions by a first fluid pressure operated cylinder. A second fluid pressure cylinder pays out and retracts one end portion of the wire line of a block and tackle unit for elevating and lowering a fluid pressure operated reciprocating unit axially disposed on a post top to be driven into the ground.
U.S. Pat. No. 5,107,935 describes an accessory for a jackhammer comprising a clamping means for gripping the upper end of the stake so that the user can controllably drive the stake into the ground. The accessory includes a stake receiver that has a channel into which the end portion of the stake is inserted and further includes a jaw and clamping means for forcibly retaining the jaw against the inserted stake. The channel includes guide ways that permit it to be used interchangeably with the more common sizes and shapes of stakes.
U.S. Pat. No. 5,088,567 shows a device having a plurality of guides and a striking mass movable by a hydraulic cylinder. The hydraulic cylinder is arranged with its longitudinal axis outside the path of the center of gravity of the striking mass. The striking mass can comprise a first elastomeric and/or plastic component and a second heavy metal component. Three guides, which can be parallel to the movement path of the center of gravity, are provided for guidance of the striking mass, the striking mass is preferably constructed to be guided at its respective areas.
U.S. Pat. No. 5,010,710 shows rods, tubes posts, and the like rod structures driven into the ground by a device which is successively clamped to selected intermediate portions of the lengths of these rods to avoid heretofore involved awkwardness, instability, and unsafe driving conditions encountered when the top ends of long rods are engaged to force the rods into the ground. The device is easily and quickly clamped to the rod at a level close to the ground to be impacted by a driving tool such as a jackhammer at a convenient reachable level, it is easily released from the rod and raised to a starting level and then reclamped for the next driving increment. The successive raising and driving steps are repeated until the rod is driven to a desired depth in the ground. When the top end of the rod approaches ground level, the device can be mounted over this end and impacted to drive the rod further into the ground. A driving shank is slidably retained in a socket of the device spaced laterally from the clamp rod and inclined toward the rod so that the device will deliver type impact blow substantially along the axis of the rod to minimize bending. The device is especially useful for rods, which drive ground anchors into the ground.
U.S. Pat. No. 5,819,857 describes a portable power driven post driver having an inner hollow cylinder open at its upper end and adapted to receive a post through a locking mechanism located at its lower end. The inner cylinder is located within an outer surface of the outer cylinder; the longitudinal axes of the two fluid powered cylinders being in alignment. A common piston rod extends between the two pistons and is attached by a fastening member to the inner cylinder, the fastening member extending through a slot in the outer cylinder. A valve receives compressed fluid, such as compressed air, and cyclically and alternately directs the compressed fluid to the two fluid powered cylinders to alternately raise the outer cylinder above the inner cylinder and to drive the upper cylinder downwardly into post driving contact with the upper end of a post held by the inner cylinder.
U.S. Pat. No. 4,665,994 teaches a portable hand held post driver which is fully operable by a single worker and which uses a fluid powered cylinder to drive posts into the ground. The cylinder raises a balanced driving weight and forces the weight down onto the post. The cylinder is reversed automatically at both the top and bottom of its stroke to automatically repeat the driving strokes so long as the operator holds a hand lever. The post is clamped to the frame of the implement by a clamp having an overcenter control linkage. Before the implement can be operated, a safety-linking pin must be intentionally released by operating a safety lever.
Additional examples of the prior art are found in U.S. Pat. No. 839,246; 904,528; 1,102,652; 2,703,479; 3,036,482; 4,665,994 and 4,872,514.
The present invention relates to a stake/post driver comprising a hammer assembly and a hammer guide assembly for use with a handheld jackhammer to mechanically drive a stake or post into the ground or other support surface.
The hammer assembly comprises a hammer element configured to strike the stake or post coupled to the handheld jackhammer by a hammer spindle. The hammer element comprises a hammer member having a centrally disposed tapered recess formed therein to receive the lower portion of the hammer spindle. The hammer spindle includes a bit formed on the upper portion thereof to couple the stake/post driver to the handheld jackhammer and a tapered lower portion to be press fit into the centrally disposed tapered recess.
The hammer guide assembly comprises a hammer housing to receive the hammer element and a portion of the hammer spindle therein having an upper spindle guide formed on the upper portion thereof to receive a portion of the hammer spindle therethrough and a lower stake/post guide coupled to the lower portion thereof to receive a portion of the stake or post therethrough to cooperatively align the hammer element relative to the stake or post during operation of the stake/post driver.
The stake/post driver may further include a hammer assembly limit to limit the longitudinal movement of the hammer assembly relative to the hammer housing to prevent the hammer member element from engaging of the lower stake/post guide as the hammer assembly moves reciprocally within the hammer housing during operation of the stake/post driver.
In use, the upper end portion of a stake or post to be driven into the ground is placed through the centrally disposed guide aperture of the lower stake/post guide and into the lower portion of of the hammer housing. The handheld jackhammer provides the hammering force against the stake or post of sufficient magnitude and frequency to drive the stake or post end into the ground to the desired depth.
It should be noted that the hammer assembly is movable laterally relative to the hammer guide assembly such that the hammer element may be aimed or directed against the upper portion of the stake or post even when the post is not vertical; while, maintaining the lower portion of the hammer housing in surrounding relationship relative to the upper portion of the stake or post.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.